A thing to remember here is that these posts are strictly meant for the particular planet position. Like, today we are looking at Mercury in Sagittarius, so the description given here may change for you if your Mercury is although in the sign of Sagittarius but with conjunction with or aspected by other planets.
So, lets see what Mercury can do in Sagittarius without any conjunction or aspect from any other planet. 1st lets see what these 2 things represent --
Mercury represents communication skills, marketing, calculative ability, younger siblings, hobbies, skills with hands, intelligence, quick decision making, logical thinking, youthfulness etc.
Sagittarius is the 9th sign of zodiac belt, hence it represents many things related with the 9th house of horoscope like Religion, Knowledge, Wisdom, Higher Learnings, Gurus, Teachings from your Father etc. Besides it also represents Coaching, Universities, Professors and Preachers, Higher Wisdom, Written Law of the Land etc. Sagittarius has next set of 2 and half nakshatra which are Mula, Purva-Ashadha and Uttara-Ashadha. Sagittarius' lord is Jupiter.
So, when Mercury is coming into Sagittarius then this person is all about gaining and sharing more and more knowledge and education. They can be forever students and forever teachers. Even if they don't go into academics, they will always be very preachy by nature. They may be interested in gaining religious or philosophical education too. They can be seen as religious teachers or preachers or Gurus. If person is interested to know about the world, this is best position among all. They also love to travel to different parts of world.
Again, impact of Mercury's effect in Sagittarius will be controlled by the various nakshatra Mercury might be in. Like, if Mercury is in Moola nakshatra, its lord Ketu's position will effect Mercury. If Mercury is in Purva-Phalguni nakshatra, then its lord Venus will impact Mercury. If Mercury is in Uttara-Phalguni nakshatra, then its lord Sun will impact Mercury.
As discussed above, we have to look at position and condition of lord of Sagittarius, i.e. Jupiter, to finally come to know what is going on with this Mercury. So, overall reading is much more necessary than a particular planet in sign position.
Tomorrow, Mercury in Capricorn.
Vishal S Saxena - Astrologer